The present invention relates to a novel brassinosteroid derivative, to a preparing process thereof, to a plant growth regulating composition comprising it, and to a method for regulating plant growth and leads to both quantitative improvements such as plant growth promotion and increasing yield, and qualitative improvements such as advance in quality and progress against stress in agriculture and horticulture
Since brassinolide was discovered as a plant growth regulating substance in pollen of Brassica napa L. (M.D. Grove et al, Nature 281, p. 216, 1979), and epi-brassinolides by Thompson et al (J. Org. Chem., 44, p. 5002, 1979) was synthesized, numbers of brassinosteroids have been found in natural products, and novel derivatives by synthesis have been reported, which are described in detail in a recent review (Yukigoseikagaku, 43,p. 849, 1985).
It has been confirmed that brassinolide and its related compounds exhibit a growth regulating activity to plant, such as lamina joint inclination of rice plant, and various investigations have been continued in search of valuable industrial utilization. However, ever known brassinosteroids show so short-term effect on plants that they are unsuitable for demand to durable activity. Any brassinosteroids which would exhibit a durable effect on plant might be evaluated highly in industry, so that such brassinosteroids have been expected.
The present invention, a result of intensive investigations, has succeeded in finding the substance able to serve the purpose, and thus has been accomplished.